CN113267203A

CN113267203A - Position detection device, lens module and camera device

Info

Publication number: CN113267203A
Application number: CN202110087677.3A
Authority: CN
Inventors: 蔡永福
Original assignee: TDK Corp
Current assignee: TDK Corp
Priority date: 2020-02-14
Filing date: 2021-01-22
Publication date: 2021-08-17
Anticipated expiration: 2041-01-22
Also published as: JP7120264B2; US20210255001A1; CN113267203B; JP2021128088A

Abstract

The position detection device of the present invention includes: the magnetic sensor includes a magnetic sensor, a first magnetic field generating unit, and a second magnetic field generating unit. The first magnetic field generating unit includes a first magnet having a first magnetic material as a main component and having a first shape, and generates a first magnetic field. The second magnetic field generating unit includes a second magnet having a second magnetic material as a main component and a second shape, generates a second magnetic field, and is provided to be movable in the first direction with respect to the first magnetic field generating unit and the magnetic sensor. The magnetic sensor generates a detection signal corresponding to a direction of a detection target magnetic field composed of a first magnetic field along the first surface and a second magnetic field along the first surface, and can detect a change in position of the second magnetic field generating unit.

Description

Position detection device, lens module and camera device

Technical Field

The present invention relates to a position detection device, a lens module, and an imaging device each including a magnetic sensor.

Background

Heretofore, a position detection apparatus using a magnetic sensor has been proposed. The present applicant has already proposed a camera module provided with a position detection device (see, for example, patent document 1). In the camera module, a position detection device detects the position of a lens that moves when focused. Patent document 2 proposes a lens driving device having a position detection magnet and a magnetic detection member. The position detection magnet detects a moving position of the lens holding member.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-163023

Patent document 2: international publication No. 2018/051729 specification

Disclosure of Invention

However, such a position detection device is required to have higher position detection accuracy.

Therefore, it is desirable to provide a position detection device, a lens module, and an imaging device that can exhibit high detection accuracy.

The position detection device according to one embodiment of the present invention includes a magnetic sensor, a first magnetic field generating unit, and a second magnetic field generating unit. The first magnetic field generating unit includes a first magnet having a first magnetic material as a main component and having a first shape, and generates a first magnetic field. The second magnetic field generating unit includes a second magnet having a second magnetic material as a main component and a second shape, generates a second magnetic field, and is provided to be movable in the first direction with respect to the first magnetic field generating unit and the magnetic sensor. The magnetic sensor generates a detection signal corresponding to a direction of a detection target magnetic field composed of a first magnetic field along the first surface and a second magnetic field along the first surface, and can detect a change in position of the second magnetic field generating unit.

A position detection device according to another embodiment of the present invention includes a magnetic sensor, a first magnetic field generating unit, and a second magnetic field generating unit. The first magnetic field generating section includes a first magnet having a first magnetic permeability and containing a first magnetic material as a main component, and generates a first magnetic field. The second magnetic field generating unit includes a second magnet having the first magnetic material as a main component and having a second magnetic permeability identical to the first magnetic permeability, generates a second magnetic field, and is provided to be movable in the first direction with respect to the first magnetic field generating unit and the magnetic sensor. The magnetic sensor generates a detection signal corresponding to a direction of a detection target magnetic field composed of a first magnetic field in a predetermined plane and a second magnetic field in the predetermined plane, and can detect a change in position of the second magnetic field generating unit.

A lens module according to another embodiment of the present invention includes the above position detection device. An imaging device according to another embodiment of the present invention includes the lens module.

Drawings

Fig. 1 is a schematic perspective view showing an overall configuration example of an imaging device including a lens module including a position detection device according to a first embodiment of the present invention.

Fig. 2 is a schematic explanatory view of the inside of the image pickup apparatus shown in fig. 1.

Fig. 3 is a schematic explanatory view of a main part of the position detection device shown in fig. 1.

Fig. 4 is a schematic explanatory view of a main part of the driving apparatus shown in fig. 1.

Fig. 5 is a side view showing a main part of the driving apparatus shown in fig. 1.

Fig. 6 is a schematic perspective view of a main portion of the position detection apparatus shown in fig. 1.

Fig. 7 is a circuit diagram showing a circuit configuration of a magnetic sensor of the position detection device shown in fig. 1.

Fig. 8 is a perspective view showing a part of the 1 magnetic detection element of fig. 7.

Fig. 9 is an explanatory diagram showing the first magnetic field, the second magnetic field, and the combined magnetic field of the position detection device shown in fig. 1.

Fig. 10A is a characteristic diagram showing a detection error of the position detection device as a reference example.

Fig. 10B is a characteristic diagram showing detection errors of the position detection device as an experimental example.

Description of the symbols

100 image pickup device

200 image sensor

300 lens module

1 position detection device

3 drive device

4 control part

5 lens

6 casing

7 substrate

7a above

7K opening part

11 first magnetic field generating part

12 second magnetic field generating part

13. 31A,34A magnet

14 first holding member

15 second holding member

16 first line

17 second wire

20. 30 magnetic sensor

41-46 coil

150 MR element

162 lower electrode

163 upper electrode

151 magnetization free layer

152 nonmagnetic layer

153 magnetization fixed layer

154 antiferromagnetic layer

MF1 first magnetic field

MF2 second magnetic field

MF synthetic magnetic field

Detailed Description

Embodiments for carrying out the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below all represent preferred specific examples of the present invention. Therefore, the numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection forms, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the components of the following embodiments, components that are not recited in the independent claims indicating the uppermost concept of the present invention will be described as arbitrary components. Each drawing is a schematic diagram, and the illustration is not necessarily strict. In the drawings, substantially the same components are denoted by the same reference numerals, and redundant description is omitted or simplified. The following description is made in the order described below.

1. One embodiment

An example of an imaging device including a lens module having: the magnetic field sensor includes a first magnetic field generating unit that generates a first magnetic field for driving the lens, a second magnetic field generating unit that generates a second magnetic field and moves integrally with the lens, and a magnetic sensor for detecting a position of the lens.

2. Modification example

<1 > an embodiment

[ Structure of imaging device 100 ]

First, referring to fig. 1 and 2, a configuration of an image pickup apparatus 100 according to an embodiment of the present invention will be described.

Fig. 1 is a perspective view showing an overall configuration example of an imaging apparatus 100. Fig. 2 is a schematic explanatory diagram of the inside of the image pickup apparatus 100. In fig. 2, for convenience of understanding, the components of the imaging apparatus 100 are illustrated in different sizes and arrangements from the corresponding components illustrated in fig. 1.

The imaging apparatus 100 constitutes, for example, a part of a camera for a smartphone, and the camera includes an optical camera shake correction mechanism and an autofocus mechanism. The imaging apparatus 100 includes, for example: an image sensor 200 as an imaging element for acquiring an image using CMOS or the like, and a lens module 300 for introducing light from a subject to be photographed into the image sensor 200.

[ Structure of lens Module 300 ]

The lens module 300 includes: the position detecting device 1, the driving device 3, the lens 5, the housing 6, and the substrate 7 of one embodiment of the present invention. The position detection device 1 is a magnetic position detection device, and detects the position of the lens 5 when automatically focusing incident light so that light incident from a subject (hereinafter, simply referred to as incident light) is focused on the imaging surface of the image sensor 200. The driving device 3 moves the lens 5 in order to focus the incident light. The housing 6 houses and protects the position detection device 1, the drive device 3, and the like. The substrate 7 has an upper face 7 a. In fig. 1, the substrate 7 is omitted; in fig. 2, the housing 6 is omitted.

Here, as shown in fig. 1 and 2, a U axis, a V axis, and a Z axis are defined. The U, V and Z axes are orthogonal to each other. In the present embodiment, the Z axis is perpendicular to the upper surface 7a of the substrate 7, and both the U axis and the V axis are parallel to the upper surface 7a of the substrate 7. In the present embodiment, the + Z direction is defined as an upward direction, and the-Z direction is defined as a downward direction.

(lens 5)

The lens 5 is disposed above the upper surface 7a of the substrate 7 in a posture in which the optical axis direction thereof coincides with the Z axis. The substrate 7 has an opening 7K, not shown, and the opening 7K allows light transmitted through the lens 5 to pass therethrough. As shown in fig. 2, the lens module 300 positions the image sensor 200 so that light from the subject passing through the lens 5 and the opening 7K of the substrate 7 in this order enters the image sensor 200.

(position detecting device 1 and Driving device 3)

Next, the position detection device 1 and the drive device 3 according to the present embodiment will be described in detail with reference to fig. 2 to 5. Fig. 3 is a perspective view showing the position detection device 1 and the drive device 3 in the lens module 300. FIG. 4 is a perspective view showing a plurality of coils 41 to 46 of the driving device 3. Fig. 5 is a side view showing a main part of the driving device 3.

The position detecting device 1 has a first holding member 14, a second holding member 15, a plurality of first wires 16, and a plurality of second wires 17. The second holding member 15 holds the lens 5. The second holding member 15 has, for example, a cylindrical shape, and the cylindrical shape is configured such that the lens 5 can be mounted inside the second holding member 15. The position detection device 1 may not have the first wire 16 and the second wire 17.

The second holding member 15 is provided with: the first holding member 14 is movable in the optical axis direction of the lens 5, i.e., the Z-axis direction. In the present embodiment, the first holding member 14 has a box-like shape configured to be able to house the lens 5 and the second holding member 15 inside the first holding member 14. The plurality of second wires 17 connect the first holding member 14 and the second holding member 15, and support the second holding member 15 so that the second holding member 15 can move in the Z-axis direction with respect to the first holding member 14.

The first holding member 14 is configured to: the counter substrate 7 is movable in both the U-axis direction and the V-axis direction above the upper surface 7a of the substrate 7. The plurality of first wires 16 connect the substrate 7 and the first holding member 14, and support the first holding member 14 so that the first holding member 14 can move in the U-axis direction and the V-axis direction with respect to the substrate 7. If the position of the first holding member 14 relative to the substrate 7 changes, the position of the second holding member 15 relative to the substrate 7 also changes.

The position detection device 1 further includes: a first magnetic field generating unit 11 that generates a first magnetic field MF1, a second magnetic field generating unit 12 that generates a second magnetic field MF2, and a magnetic sensor 20. The first magnetic field generating unit 11 includes 2 first magnets arranged at different positions from each other. Specifically, the first magnetic field generating portion 11 has the magnet 31A and the magnet 34A as the 2 first magnets described above. First magnetic field MF1 is a resultant magnetic field of the magnetic fields generated by magnet 31A and magnet 34A, respectively. The magnet 31A and the magnet 34A have the first magnetic material as a main component, and have, for example, a rectangular parallelepiped shape. The first magnetic material may be a neodymium-based magnet material such as NdFeB (neodymium iron boron magnet), and specifically, NdFeB of grade N48H is preferably used. The magnet 31A and the magnet 34A have a temperature coefficient of the first residual magnetic flux density. The magnet 31A and the magnet 34A are fixed in the first holding member 14. That is, the first magnetic field generating portion 11 is held by the first holding member 14. The magnet 31A and the magnet 34A are driving magnets, and generate a driving force for moving the second holding member 15 holding the lens 5 along the Z axis. The

magnets

31A and 34A may be bias magnets for biasing the magnetic sensor 20.

As shown in fig. 3, the magnet 31A has an end face 31A1 located at the end in the + U direction of the magnet 31A. The magnet 34A has an end face 34A1 located at the end of the magnet 34A in the-V direction.

The second magnetic field generating section 12 is provided with: the position relative to the first magnetic field generating portion 11 may be changed. The second magnetic field generating portion 12 has, for example, a magnet 13. Thus, the second magnetic field MF2 is the magnetic field generated by the magnet 13. The magnet 13 has a second magnetic material different from the first magnetic material as a main component, and has, for example, a rectangular parallelepiped shape similar to the magnet 31A and the magnet 34A. However, the shape of the magnet 13 is different from the shapes of the magnet 31A and the magnet 34A. That is, the shape of the magnet 13 is different from and dissimilar to the shapes of the magnet 31A and the magnet 34A. As the second magnetic material, for example, a neodymium-based magnet material such as NdFeB is cited, and specifically, NdFeB of grade N48SH is suitably used. Alternatively, SmCo (samarium cobalt magnet) as the second magnetic material may be used. The magnet 13 may have a temperature coefficient of the second residual magnetic flux density. Here, the absolute value of the temperature coefficient of the second residual magnetic flux density that the magnet 13 has is preferably smaller than the absolute value of the temperature coefficient of the first residual magnetic flux density that the magnet 31A and the magnet 34A have. The magnet 13 is a position detection magnet, and generates a second magnetic field MF2 for detecting the position of the second holding member 15 that holds the lens 5.

In addition, the magnet 13 is fixed in the second holding member 15 so as to be located in a space near the end face 31A1 (fig. 3) of the magnet 31A and the end face 34A1 (fig. 3) of the magnet 34A. That is, the second magnetic field generating portion 12 is held by the second holding member 15. If the position of the second holding member 15 relative to the first holding member 14 changes along the Z-axis direction, the position of the second magnetic field generating portion 12 relative to the first magnetic field generating portion 11 also changes along the Z-axis direction.

The magnetic sensor 20 detects the detection target magnetic field at the predetermined detection position where the magnetic sensor is disposed, and generates a detection signal corresponding to the direction of the detection target magnetic field. The magnetic sensor 20 is fixed to the substrate 7 so as to be positioned in the vicinity of both the end face 31A1 of the magnet 31A and the end face 34A1 of the magnet 34A. The distance from the magnet 31A to the magnetic sensor 20 is preferably substantially equal to the distance from the magnet 34A to the magnetic sensor 20. The magnet 13 is disposed above the magnetic sensor 20, for example.

In the present embodiment, the predetermined detection position is a position where the magnetic sensor 20 is disposed. As described above, if the position of the second magnetic field generating unit 12 changes with respect to the position of the first magnetic field generating unit 11, the distance between the predetermined detection position and the second magnetic field generating unit 12 changes. The detection target magnetic field is a combined magnetic field MF of the first magnetic field MF1 and the second magnetic field MF2 at the detection position. The magnetic sensor 20 can detect a change in the position of the second magnetic field generating unit 12 by detecting the combined magnetic field MF. The first magnetic field MF1 and the second magnetic field MF2 are illustrated in fig. 6 described later. The synthesized magnetic field MF is shown in fig. 9 described later. The positional relationship among the first magnetic field generating unit 11, the second magnetic field generating unit 12, and the magnetic sensor 20, and the configuration of the magnetic sensor 20 will be described in detail later.

The drive device 3 is configured to include

magnets

31A,31B,32A,32B,33A,33B,34A,34B and coils 41,42,43,44,45, 46. As shown in fig. 1 and 2, the magnet 31A is located in the-V direction as viewed from the lens 5. The magnet 32A is located in the + V direction as viewed from the lens 5. The magnet 33A is located in the-U direction as viewed from the lens 5. The magnet 34A is located in the + U direction as viewed from the lens 5. The

magnets

31B,32B,33B,34B are located above (+ Z direction) the

magnets

31A,32A,33A,34A, respectively. In addition, the

magnets

31A,31B,32A,32B,33A,33B,34A,34B are held in the first holding member 14.

As shown in fig. 3, the

magnets

31A,31B,32A,32B each have a rectangular parallelepiped shape with the U-axis direction being the long direction. The

magnets

33A,33B,34A,34B each have a rectangular parallelepiped shape with the V-axis direction being the long direction. The direction of magnetization of the

magnets

31A,32B is the + V direction. The direction of magnetization of the

magnets

31B,32A is the-V direction. The direction of magnetization of the

magnets

33A,34B is the + U direction. The direction of magnetization of the

magnets

33B,34A is the-U direction. In fig. 5, arrows in the

magnets

31A,31B indicate directions of magnetization of the

magnets

31A,31B, respectively.

As shown in fig. 1 and 2, the coil 41 is disposed between the magnet 31A and the substrate 7. The coil 42 is disposed between the magnet 32A and the substrate 7. The coil 43 is disposed between the magnet 33A and the substrate 7. The coil 44 is disposed between the magnet 34A and the substrate 7. The coil 45 is disposed between the

magnets

31A,31B and the lens 5. The coil 46 is disposed between the

magnets

32A,32B and the lens 5. Further, the

coils

41,42,43,44 are fixed to the substrate 7, respectively. The

coils

45,46 are each fixed in the second holding member 15.

For the coil 41, a magnetic field generated from the magnet 31A is mainly applied. For the coil 42, a magnetic field generated from the magnet 32A is mainly applied. For the coil 43, a magnetic field generated from the magnet 33A is mainly applied. For the coil 44, a magnetic field generated from the magnet 34A is mainly applied.

As shown in fig. 2,4, and 5, the coil 45 includes: a first conductor portion 45A extending along the U axis extending from the magnet 31A, a second conductor portion 45B extending along the U axis extending from the

magnet

31B, and 2

third conductor portions

45C,45D connecting the first conductor portion 45A and the second conductor portion 45B. As shown in fig. 4, the coil 46 includes: a first conductor portion 46A extending along the U axis extending from the magnet 32A, a second conductor portion 46B extending along the U axis extending from the

magnet

32B, and 2

third conductor portions

46C,46D connecting the first conductor portion 46A and the second conductor portion 46B.

The first conductor portion 45A of the coil 45 is mainly applied with a component in the + V direction of the magnetic field generated from the magnet 31A. To the second conductor portion 45B of the coil 45, a component in the-V direction of the magnetic field generated from the magnet 31B is mainly applied. To the first conductor portion 46A of the coil 46, a component of the-V direction of the magnetic field generated from the magnet 32A is mainly applied. To the second conductor portion 46B of the coil 46, a component in the + V direction of the magnetic field generated from the magnet 32B is mainly applied.

The drive device 3 further includes 4 magnetic sensors 30 fixed to the substrate 7 inside the coils 41 to 44, respectively. As described later, the 4 magnetic sensors 30 are used when the position of the lens 5 is changed in order to reduce the influence of hand trembling.

The magnetic sensor 30 located inside the coil 41 detects the magnetic field generated from the magnet 31A, and generates a signal corresponding to the position of the magnet 31A. The magnetic sensor 30 located inside the coil 42 detects the magnetic field generated from the magnet 32A, and generates a signal corresponding to the position of the magnet 32A. The magnetic sensor 30 located inside the coil 43 detects the magnetic field generated from the magnet 33A, and generates a signal corresponding to the position of the magnet 33A. The magnetic sensor 30 located inside the coil 44 detects the magnetic field generated from the magnet 34A, and generates a signal corresponding to the position of the magnet 34A. The magnetic sensor 30 may be formed of an element that detects a magnetic field, such as a hall element. The drive device 3 may include only one of the magnetic sensor 30 positioned inside the coil 41 and the magnetic sensor 30 positioned inside the coil 42. Similarly, the drive device 3 may have only one of the magnetic sensor 30 located inside the coil 43 and the magnetic sensor 30 located inside the coil 44.

Next, the positional relationship among the first magnetic field generating unit 11, the second magnetic field generating unit 12, and the magnetic sensor 20 will be described in detail with reference to fig. 3 and 6. Fig. 6 is a perspective view showing a main part of the position detection device 1. Here, as shown in fig. 6, the + X direction and the + Y direction are defined. The + X direction and the + Y direction are both directions parallel to the upper surface 7a (see fig. 2) of the substrate 7. The + X direction is a direction rotated by 45 ° from the + U direction toward the + V direction. The + Y direction is a direction rotated by 45 DEG from the + V direction toward the-U direction. The direction opposite to the + X direction is defined as the-X direction, and the direction opposite to the + Y direction is defined as the-Y direction.

In fig. 6, an arrow denoted by reference numeral MF1 indicates the first magnetic field MF1 at the detection position. In the present embodiment, the first magnetic field generating unit 11 and the magnetic sensor 20 are provided with: the direction of the first magnetic field MF1 at the detection position is the-Y direction. The direction of the first magnetic field MF1 at the detection position can be adjusted, for example, according to the position of the

magnets

31A,34A with respect to the magnetic sensor 20 and the orientation of the

magnets

31A,34A with respect to the magnetic sensor 20. The

magnets

31A,34A are preferably arranged in a symmetrical manner to the YZ plane including the detection position.

In fig. 6, an arrow denoted by MF2 indicates the second magnetic field MF2 at the detection position, and an arrow inside the magnet 13 indicates the magnetization of the magnet 13. In the detection position, the relative angle between the direction of the second magnetic field MF2 and the direction of the first magnetic field MF1 is represented by symbol θ. The relative angle θ is represented by a value in the range of 0 ° to 180 °.

In the present embodiment, the first magnetic field generating unit 11, the second magnetic field generating unit 12, and the magnetic sensor 20 are disposed such that the relative angle θ is greater than 90 ° and less than 180 °. The relative angle θ can be adjusted according to the posture of the magnet 13, for example. Fig. 6 shows an example in which the relative angle θ is 135 °. In this example, the magnet 13 is disposed in a posture in which the magnetization direction of the magnet 13 is rotated by 45 ° from the-X direction toward the-Y direction.

Next, the structure of the magnetic sensor 20 will be described with reference to fig. 7. Fig. 7 is a circuit diagram showing the configuration of the magnetic sensor 20. In the present embodiment, the magnetic sensor 20 is configured as follows: a detection signal corresponding to an angle formed by the direction of the combined magnetic field MF with respect to the reference direction is generated as a detection signal corresponding to the direction of the detection target magnetic field. The reference direction is the direction of the first magnetic field MF1, i.e., the-Y direction.

As shown in fig. 7, the magnetic sensor 20 has a wheatstone bridge circuit 21 and a differential detector 22. The wheatstone bridge circuit 21 includes a power port V, a ground port G, 2 output ports E1, E2, a first pair of magnetic sensing elements R1, R2 connected in series, and a second pair of magnetic sensing elements R3, R4 connected in series. One end of each of the magnetic sensing elements R1 and R3 is connected to the power supply port V. The other end of the magnetic detection element R1 is connected to one end of the magnetic detection element R2 and the output port E1. The other end of the magnetic detection element R3 is connected to one end of the magnetic detection element R4 and the output port E2. The other end of each of the magnetic sensing elements R2 and R4 is connected to the ground port G. A power supply voltage of a predetermined magnitude is applied to the power supply port V. The ground port G is grounded.

In the present embodiment, each of the magnetic detection elements R1 to R4 includes a plurality of magnetoresistive effect elements (MR elements) connected in series. Each of the plurality of MR elements is, for example, a spin valve type MR element. The spin valve type MR element includes: the magnetic sensor includes a magnetization pinned layer having a fixed magnetization direction, a free layer that is a magnetic layer having a magnetization direction that changes according to the direction of a magnetic field to be detected, and a nonmagnetic layer disposed between the magnetization pinned layer and the free layer. The spin valve type MR element may be a TMR element or a GMR element. In the TMR element, the nonmagnetic layer is a tunnel barrier layer. In the GMR element, the nonmagnetic layer is a nonmagnetic conductive layer. In the spin valve type MR element, the resistance value changes according to the angle formed by the magnetization direction of the free layer and the magnetization direction of the magnetization fixed layer, and the resistance value is the smallest when the angle is 0 ° and the resistance value is the largest when the angle is 180 °. In fig. 7, black arrows indicate the magnetization direction of the magnetization pinned layer of the MR element, and white arrows indicate the magnetization direction of the free layer of the MR element.

The magnetization direction of the magnetization pinned layers of the plurality of MR elements included in the magnetic detection elements R1, R4 is the-Y direction, and the magnetization direction of the magnetization pinned layers of the plurality of MR elements included in the magnetic detection elements R2, R3 is the + Y direction. In this case, the potential difference between the output ports E1, E2 changes in accordance with the cosine of the angle that the direction of the combined magnetic field MF makes with respect to the-Y direction. The differential detector 22 outputs a signal corresponding to the potential difference between the output ports E1 and E2 as a detection signal. Therefore, the magnetic sensor 20 detects the combined magnetic field MF, and generates a detection signal corresponding to the cosine of the angle formed by the direction of the combined magnetic field MF with respect to the-Y direction.

In view of the manufacturing accuracy of the MR elements, the magnetization direction of the magnetization pinned layers of the plurality of MR elements may be slightly deviated from the above-described direction.

Here, an example of the structure of the magnetic detection element will be described with reference to fig. 8. Fig. 8 is a perspective view showing a part of 1 magnetic detection element of the magnetic sensor 20 shown in fig. 7. In this example, 1 magnetic detection element has a plurality of lower electrodes 162, a plurality of magnetoresistance effect (MR) elements 150, and a plurality of upper electrodes 163. The plurality of lower electrodes 162 are disposed on a substrate not shown. Each lower electrode 162 has an elongated shape. Gaps are formed between 2 lower electrodes 162 adjacent in the longitudinal direction of the lower electrode 162. As shown in fig. 8, the MR elements 150 are disposed near both ends in the longitudinal direction on the upper surface of the lower electrode 162. The MR element 150 includes, for example, a magnetization free layer 151, a nonmagnetic layer 152, a magnetization fixed layer 153, and an antiferromagnetic layer 154 laminated in this order from the lower electrode 162 side. The magnetization free layer 151 is electrically connected to the lower electrode 162. The antiferromagnetic layer 154 is configured to include an antiferromagnetic material, and generates an exchange connection with the magnetization pinned layer 153 to fix the direction of magnetization of the magnetization pinned layer 153. The plurality of upper electrodes 163 are disposed on the plurality of MR elements 150. Each of the upper electrodes 163 has an elongated shape, and is used to electrically connect the antiferromagnetic layers 154 of the adjacent 2 MR elements 150 to each other, and the 2 MR elements 150 are disposed on the adjacent 2 lower electrodes 162 in the longitudinal direction of the lower electrodes 162. Due to such a configuration, the magnetic detection element shown in fig. 8 includes a plurality of MR elements 150, and the plurality of MR elements 150 are connected in series to the plurality of upper electrodes 163 via the plurality of lower electrodes 162. The arrangement of the magnetization free layer 151, the nonmagnetic layer 152, the magnetization pinned layer 153, and the antiferromagnetic layer 154 of the MR element 150 may be vertically reversed from the arrangement shown in fig. 8.

Next, the operation of the driving device 3 will be described with reference to fig. 1 to 5. First, the optical camera shake correction mechanism and the autofocus mechanism will be briefly described. The drive device 3 constitutes a part of the optical handshake compensating mechanism and the autofocus mechanism. The driving device 3, the optical camera shake correction mechanism, and the autofocus mechanism are controlled by a control unit 4 (see fig. 1) provided outside the imaging device 100.

The optical camera shake correction mechanism is configured to, for example: hand shake can be detected by a gyro sensor or the like outside the imaging apparatus 100. If the optical camera shake correction mechanism detects camera shake, the control unit 4 controls the drive device 3 so as to change the position of the lens 5 with respect to the substrate 7 in accordance with the camera shake. This stabilizes the absolute position of the lens 5, and reduces the influence of camera shake. The position of the lens 5 relative to the substrate 7 changes in the direction parallel to the U axis or the direction parallel to the V axis according to the state of hand shake.

The autofocus mechanism is configured, for example, as follows: the focus state on the subject can be detected by the image sensor 200, the autofocus sensor, or the like. The control unit 4 changes the position of the lens 5 with respect to the substrate 7 along the Z axis by the driving device 3 to focus on the subject. This enables automatic focusing of the subject.

Next, the operation of the drive device 3 related to the optical camera shake correction mechanism will be described. If a current is caused to flow through the

coils

41,42 by the control section 4; the first holding member 14 to which the

magnets

31A,32A are fixed moves along the V-axis due to the interaction of the magnetic field generated from the

magnets

31A,32A and the magnetic field generated from the

coils

41, 42. As a result, the lens 5 also moves along the V axis. In addition, if the control unit 4 causes a current to flow through the

coils

43, 44; the first holding member 14 to which the

magnets

33A,34A are fixed moves along the U-axis due to the interaction of the magnetic field generated from the

magnets

33A,34A and the magnetic field generated from the

coils

43, 44. As a result, the lens 5 also moves along the U axis. The control unit 4 detects the position of the lens 5 by measuring signals generated by the magnetic sensor 30 and corresponding to the positions of the

magnets

31A,32A,33A, and 34A.

Next, the operation of the driving device 3 related to the autofocus mechanism will be described. When the position of the lens 5 relative to the substrate 7 is moved along the Z axis, the control unit 4 causes a current to flow through the coil 45 such that a current in the + U direction flows through the first conductor 45A and a current in the-U direction flows through the second conductor 45B. The controller 4 further causes a current to flow through the coil 46 such that a current flows in the-U direction in the first conductor portion 46A and a current flows in the + U direction in the second conductor portion 46B. By these currents and the magnetic fields generated from the

magnets

31A,31B,32A,32B, the first and

second conductor portions

45A, 45B of the coil 45 and the first and

second conductor portions

46A, 46B of the coil 46 are applied with lorentz forces in the + Z direction. Thereby, the second holding member 15 to which the

coils

45,46 are fixed moves in the + Z direction. As a result, the lens 5 also moves in the + Z direction.

When the lens 5 is moved in the-Z direction with respect to the position of the substrate 7, the control unit 4 causes a current to flow through the

coils

45,46 in a direction opposite to the current direction when the lens is moved in the + Z direction.

[ Effect of the image pickup apparatus 100 ]

Next, the operation and effects of the position detection device 1 of the present embodiment and the imaging device 100 including the position detection device 1 will be described. The position detection device 1 of the present embodiment is used to detect the position of the lens 5. In the present embodiment, if the position of the lens 5 with respect to the substrate 7 changes, the position of the second holding member 15 with respect to the substrate 7 and the first holding member 14 also changes. As described above, the first holding member 14 holds the first magnetic field generating portion 11, and the second holding member 15 holds the second magnetic field generating portion 12. Therefore, if the relative position of the lens 5 changes as described above, the position of the second magnetic field generating unit 12 with respect to the first magnetic field generating unit 11 also changes. Hereinafter, the position of the second magnetic field generating unit 12 relative to the first magnetic field generating unit 11 is referred to as "relative position". In the present embodiment, the direction of the relative position change is a direction parallel to the Z axis, which is the optical axis direction of the lens 5.

If the relative position changes; the position of the second magnetic field generation part 12 with respect to the substrate 7 is changed although the position of the first magnetic field generation part 11 with respect to the substrate 7 is not changed. For this reason, if the relative position changes; although the strength and direction of the first magnetic field MF1 at the detected position and the direction of the second magnetic field MF2 at the detected position do not change, the strength of the second magnetic field MF2 at the detected position changes. If the intensity of the second magnetic field MF2 at the detection position changes, the direction and intensity of the detection target magnetic field, that is, the combined magnetic field MF, also change, and accordingly, the value of the detection signal generated by the magnetic sensor 20 also changes. The value of the detection signal generated by the magnetic sensor 20 changes depending on the relative position. The control unit 4 measures the detection signal to detect the relative position.

Here, the strengths and directions of the first magnetic field MF1, the second magnetic field MF2, and the combined magnetic field MF at the detected position will be described with reference to fig. 9. Hereinafter, the magnetic field of the second magnetic field MF2 at the detection position when the distance between the detection position and the second magnetic field generating unit 12 is relatively large is referred to as MF2a, and the magnetic field of the second magnetic field MF2 at the detection position when the distance between the detection position and the second magnetic field generating unit 12 is relatively small is referred to as MF2 b. In fig. 9, the direction of the magnetic field MF2a is indicated by the direction of the arrow to which the reference MF2a is attached, and the strength of the magnetic field MF2a is indicated by the length of the arrow to which the reference MF2a is attached. Similarly, the direction of the magnetic field MF2b is indicated by the direction of the arrow to which the reference MF2b is attached, and the strength of the magnetic field MF2b is indicated by the length of the arrow to which the reference MF2b is attached. As shown in fig. 9, the strength of the magnetic field MF2b is greater than the strength of the magnetic field MF2 a. The direction of the magnetic field MF2a is the same as the direction of the magnetic field MF2 b.

Fig. 9 shows an example of the case where the relative angle θ shown in fig. 6 is 135 °. In this example, the angle that the direction of the magnetic field MF2a makes with the direction of the first magnetic field MF1 at the detection position and the angle that the direction of the magnetic field MF2b makes with the direction of the first magnetic field MF1 at the detection position are both 135 °.

The combined magnetic field of the first magnetic field MF1 and the magnetic field MF2a at the detection position is denoted by a symbol MFa, the combined magnetic field of the first magnetic field MF1 and the magnetic field MF2b at the detection position is denoted by a symbol MFb, an angle formed by the direction of the combined magnetic field MFa with respect to the-Y direction, which is the reference direction, is denoted by a symbol θ a, and an angle formed by the direction of the combined magnetic field MFb with respect to the-Y direction, which is the reference direction, is denoted by a symbol θ b. As shown in fig. 9, the angle θ b is larger than the angle θ a (θ b > θ a). As described above, the angle that the direction of the combined magnetic field MF makes with respect to the reference direction (-Y direction) changes depending on the strength of the second magnetic field MF 2. The intensity of the second magnetic field MF2 changes depending on the distance between the detection position and the second magnetic field generating unit 12. Therefore, the angle of the direction of the combined magnetic field MF with respect to the reference direction (-Y direction) varies depending on the distance between the detection position and the second magnetic field generating unit 12.

In the present embodiment, the magnetic sensor 20 generates a detection signal corresponding to the angle that the direction of the combined magnetic field MF makes with the reference direction, as a detection signal corresponding to the direction of the detection target magnetic field. According to the present embodiment, the distance between the detection position and the second magnetic field generating unit 12 can be obtained by the detection signal, and thus the relative position can be detected.

In the present embodiment, the relative angle θ shown in fig. 6 is set to be in a range of more than 90 ° and less than 180 °. Thus, according to the present embodiment, the amount of change in the angle that the direction of the combined magnetic field MF makes with respect to the reference direction is made larger than the amount of change in the relative position, and the sensitivity of position detection is improved.

In the present embodiment, the shape of the

magnets

31A,34A is different from the shape of the magnet 13. For this reason, the

magnets

31A,34A of the first magnetic field generating unit 11 can be made to have a shape suitable as a driving source for moving the lens 5 along the Z axis, and the magnet 13 of the second magnetic field generating unit 12 can be made to have a shape suitable for the magnetic sensor 20 to detect the position of the magnet 13 along the Z axis. In the present embodiment, the first magnetic material, which is the main component of the

magnets

31A,34A of the first magnetic field generating unit 11, is made different from the second magnetic material, which is the main component of the magnet 13 of the second magnetic field generating unit 12. Therefore, even if the shape of the

magnet

31A,34A of the first magnetic field generating portion 11 is different from the shape of the magnet 13 of the second magnetic field generating portion 12, the thermal demagnetization factor of the

magnet

31A,34A can be made close to the thermal demagnetization factor of the magnet 13. Therefore, in the imaging device 100, even if the temperature of the environment in which the position detection device 1 is installed changes, the position of the second magnetic field generation unit 12 with respect to the first magnetic field generation unit 11 and the magnetic sensor 20 is not easily changed. That is, the influence of the change in the ambient temperature is less likely to affect the accuracy of the position detection of the lens 5 by the magnetic sensor 20, and the temperature dependency of the accuracy of the position detection of the lens 5 by the magnetic sensor 20 can be reduced. The result is: according to the imaging apparatus 100 of the present embodiment, the position of the lens 5 can be changed more accurately, and a better image can be obtained.

In the present embodiment, by making the absolute value of the temperature coefficient of the second residual magnetic flux density of the magnet 13 smaller than the absolute value of the temperature coefficient of the first residual magnetic flux density of the magnet 31A and the magnet 34A, it is possible to further reduce the variation in the position detection of the lens 5 by the magnetic sensor 20 due to the change in the ambient temperature.

Here, fig. 10A shows the temperature characteristics of the position detection device as a reference example. In fig. 10A, the horizontal axis represents the actual displacement amount [ μm ] of the lens 5 along the Z axis, and the vertical axis represents: when the ambient temperature varies from 25 ℃ to 65 ℃, the maximum error [ μm ] of the measurement value detected by the position detection device with respect to the actual displacement amount of the lens 5 along the Z-axis. The horizontal axis displacement [ μm ] is represented by a positive value representing a + Z direction displacement and a negative value representing a-Z direction displacement, with the reference position being 0. In this reference example, NdFeB of grade N48SH was used as a constituent material of

magnets

31A,34A, and NdFeB of grade N48H was used as a constituent material of magnet 13. In this reference example, the

magnets

31A and 34A are each shaped as a rectangular parallelepiped having a length of 7mm × a width of 1mm × a thickness of 0.5mm, and the magnet 13 is shaped as a rectangular parallelepiped having a length of 1mm × a width of 0.8mm × a thickness of 0.5 mm. The result is: the thermal demagnetization rates of the

magnets

31A,34A are-3.5%, and the thermal demagnetization rate of the magnet 13 is-4.51%. As shown in fig. 10A, it is found that in the position detection device as a reference example, when the lens 5 is displaced in the range from-400 μm to +400 μm along the Z axis, an error of 6 μm occurs at maximum.

Fig. 10B shows temperature characteristics of an experimental example of the position detecting device 1 according to the present embodiment. In fig. 10B, the horizontal axis represents the actual displacement amount [ μm ] of the lens 5 along the Z axis, and the vertical axis represents: when the ambient temperature varies from 25 ℃ to 65 ℃, the maximum error [ μm ] of the measurement value detected by the position detection device with respect to the actual displacement amount of the lens 5 along the Z-axis. The horizontal axis displacement [ μm ] is, similarly to fig. 10A, the reference position 0, the + Z direction displacement with a positive value, and the-Z direction displacement with a negative value. In this experimental example, NdFeB of grade N48SH was used as a constituent material of the

magnets

31A,34A, and SmCo was used as a constituent material of the magnet 13. In the present experimental example, the

magnets

31A and 34A were each shaped as a rectangular parallelepiped having a length of 7mm × a width of 1mm × a thickness of 0.5mm, and the magnet 13 was shaped as a rectangular parallelepiped having a length of 1mm × a width of 0.8mm × a thickness of 0.5 mm. The result is: the thermal demagnetization rates of the

magnets

31A,34A are-3.5%, and the thermal demagnetization rate of the magnet 13 is also-3.5%. As shown in fig. 10B, in the present experimental example, it is found that when the lens 5 is displaced in the range from-400 μm to +400 μm along the Z axis, the maximum error can be controlled to 0.6 μm.

<2. modification >

Although the present invention has been described above by way of the embodiments, the present invention is not limited to the above embodiments, and various changes can be made. For example, in the above-described embodiment, although in the magnetic sensor, a full bridge circuit is formed using 4 magnetic detection elements; however, in the present invention, a half-bridge circuit may be formed using, for example, 2 magnetic detection elements. In addition, the shapes and sizes of the plurality of magnetoresistance effect elements may be the same as or different from each other. The dimensions of the respective components, the design of the respective components, and the like are merely examples, and are not limited thereto.

The position detection device of the present invention is not limited to a device for detecting the position of the lens, and may detect the position of an object other than the lens in space.

In addition, in the above-described embodiment, although the first magnet generates the first magnetic field and the first magnetic field is used as the drive source for driving the lens and the second holding member that holds the lens, the present invention is not limited to this. In the present invention, the first magnet may be used as a bias magnet for applying a bias voltage to the magnetoresistance effect element of the magnetic sensor, for example.

In the position detecting device 1 of the above embodiment, the first magnetic material that is the main component of the first magnetic body and the second magnetic material that is the main component of the second magnetic body are made different from each other, and the shape of the first magnetic body and the shape of the second magnetic body are made different from each other, whereby the thermal demagnetization factor of the first magnetic body and the thermal demagnetization factor of the second magnetic body are made close to each other. However, the present invention is not limited thereto. For example, the main component of the first magnetic body and the main component of the second magnetic body may be both made of the same magnetic material (for example, the first magnetic material), and the magnetic permeability of the first magnetic body (for convenience, referred to as the first magnetic permeability) and the magnetic permeability of the second magnetic body (for convenience, referred to as the second magnetic permeability) may be substantially the same. In this case, for example, the shape of the first magnet may be made the same as or similar to the shape of the second magnet. Even in this case, the thermal demagnetization rate of the first magnetic body can be made close to the thermal demagnetization rate of the second magnetic body. Therefore, the temperature characteristic of the first magnet is similar to the temperature characteristic of the second magnet, and an error in the position detection accuracy can be reduced.

According to the position detection device, the lens module, and the imaging device according to the embodiment of the present invention, high detection accuracy can be exhibited.

Further, the present technology can also adopt the following configuration.

(1)

A position detection device is provided with:

a magnetic sensor;

a first magnetic field generating section including a first magnet having a first magnetic material as a main component and having a first shape, and generating a first magnetic field; and

a second magnetic field generating unit including a second magnet that generates a second magnetic field and is provided to be movable in the first direction with respect to the first magnetic field generating unit and the magnetic sensor, the second magnet having a second magnetic material as a main component and having a second shape,

the magnetic sensor may generate a detection signal corresponding to a direction of a detection target magnetic field synthesized by the first magnetic field along a first surface and the second magnetic field along the first surface, and may detect a change in position of the second magnetic field generating unit.

(2)

The position detection apparatus of (1) above, wherein,

an absolute value of a temperature coefficient of the second residual magnetic flux density of the second magnet is smaller than an absolute value of a temperature coefficient of the first residual magnetic flux density of the first magnet.

(3)

The position detection device of the (1) or the (2), wherein,

the first magnetic material comprises NdFeB,

the second magnetic material comprises SmCo.

(4)

The position detection device of any one of the (1) to (3), wherein,

the first face is perpendicular to the first direction.

(5)

The position detection device of any one of the (1) to (4), wherein,

further comprises a first holding member and a second holding member,

the first holding member holds the first magnetic field generating portion,

the second holding member is provided to be movable in the first direction with respect to the first holding member, and holds the second magnetic field generating portion.

(6)

The position detection apparatus of (5) above, wherein,

the second holding member may hold a lens having an optical axis along the first direction.

(7)

A position detection device is provided with:

a magnetic sensor;

a first magnetic field generating section including a first magnet having a first magnetic material as a main component and having a first magnetic permeability, and generating a first magnetic field; and

a second magnetic field generating section including a second magnet that generates a second magnetic field and is provided to be movable in the first direction with respect to the first magnetic field generating section and the magnetic sensor, the second magnet having the first magnetic material as a main component and having a second magnetic permeability identical to the first magnetic permeability,

the magnetic sensor may generate a detection signal corresponding to a direction of a detection target magnetic field composed of the first magnetic field within a predetermined plane and the second magnetic field within the predetermined plane, and may detect a change in position of the second magnetic field generating unit.

(8)

A lens module includes:

a magnetic sensor;

a first magnetic field generating section including a first magnet having a first magnetic material as a main component and having a first shape, and generating a first magnetic field;

a second magnetic field generating unit including a second magnet that generates a second magnetic field and is provided to be movable in the first direction with respect to the first magnetic field generating unit and the magnetic sensor, the second magnet having a second magnetic material as a main component and having a second shape; and

a lens provided to be movable in the first direction with respect to the first magnetic field generating unit and the magnetic sensor in conjunction with the second magnetic field generating unit,

(9)

The lens module of (8), wherein,

further comprises a first holding member and a second holding member,

the first holding member holds the first magnetic field generating portion,

the second holding member is provided to be movable in the first direction with respect to the first holding member, and holds the second magnetic field generation section and the lens.

(10)

A lens module includes:

a magnetic sensor;

a first magnetic field generating section including a first magnet having a first magnetic material as a main component and having a first magnetic permeability, and generating a first magnetic field;

a second magnetic field generating section including a second magnet that generates a second magnetic field and is provided to be movable in the first direction with respect to the first magnetic field generating section and the magnetic sensor, the second magnet having the first magnetic material as a main component and having a second magnetic permeability identical to the first magnetic permeability; and

(11)

An image pickup apparatus includes an image pickup device and a lens module,

the lens module has:

a magnetic sensor;

(12)

An image pickup apparatus includes an image pickup device and a lens module,

the lens module has:

a magnetic sensor;

The present disclosure contains subject matter relating to the disclosure in japanese priority patent application JP2020-023517 filed at the japanese patent office on day 2, month 14, 2020, which is incorporated herein by reference in its entirety.

It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible in light of design requirements and other factors, but are intended to be included within the scope of the appended claims or their equivalents.

Claims

1. A position detection device is provided with:

a magnetic sensor;

2. The position detection apparatus according to claim 1,

3. The position detection apparatus according to claim 1 or claim 2,

the first magnetic material comprises NdFeB,

the second magnetic material comprises SmCo.

4. The position detection apparatus according to any one of claim 1 to claim 3,

the first face is perpendicular to the first direction.

5. The position detection apparatus according to any one of claim 1 to claim 4,

further comprises a first holding member and a second holding member,

the first holding member holds the first magnetic field generating portion,

6. The position detection apparatus according to claim 5,

7. A position detection device is provided with:

a magnetic sensor;

8. A lens module includes:

a magnetic sensor;

9. The lens module of claim 8,

further comprises a first holding member and a second holding member,

the first holding member holds the first magnetic field generating portion,

10. A lens module includes:

a magnetic sensor;

11. An image pickup apparatus includes an image pickup device and a lens module,

the lens module has:

a magnetic sensor;

12. An image pickup apparatus includes an image pickup device and a lens module,

the lens module has:

a magnetic sensor;